The invention relates to a water heater having a waterway changeover control apparatus and its related control method.
Storage electric water heaters, gas water heaters, and solar water heaters are example water heaters with their own advantages respectively. Among them, the electric water heater, installed in the wall cabinet or balcony, includes features of long service life, energy efficiency, safety, and environmental protection. However, it needs preheating prior to use and its continuous water supply typically cannot exceed its volume (i.e., the water temperature will drop after large amounts of water is used). The instantaneous gas water heater can supply hot water while the gas is burning, so that there is no limit on the hot water supply quantity. But due to the drainage of cold water in the pipe after startup, one needs to wait to use, and if one switches off the hot water during use, then the water temperature may be a little bit high after restart. The solar water heater can heat up the water by the sun, which is energy-saving, environmentally beneficial, and economic. However, the solar water heater has shortcomings such as complicated installation, inconvenient maintenance, long cold water pipe, and possible failure in cloudy or rainy days or in winter.
Although there are technical plans to join the electric water heater and the gas or solar water heater, two water heaters need switching independently, which is not only inconvenient, but also fail to make the best use of both water heaters. The patent of China No. 200520004940.4, has introduced an electric water heater that can be used jointly with solar energy. The solar water heater is connected to the electric water heater by a signal line. Below the electric water heater, there is a pipe to connect it to a mixing valve, and then valves to connect the electric water heater and the solar water heater. This connection method is not only complicated, but makes many changes to the original pipes of the user and has poor applicability.